The present invention relates to adjustable beds in general and, more particularly, to a tilt-prevention mechanism for use in adjustable beds of the type used in hospitals.
Various constructions of adjustable and/or tiltable beds and similar equipment are already known, for instance, from the U.S. Pat. Nos. 3,220,019; 3,371,358; 3,373,453; 3,462,772; 3,611,453; 3,694,830; 3,972,081 and 4,324,010. In many instances, the mattress of an adjustable hospital bed can be adjusted not only as to its elevation from the ground, but also as to its shape, i.e. it can be contoured to afford comfort to, or aid in the recovery of, the patient occupying the bed. The positional adjustment is usually achieved by means of an electric motor and a transmission arrangement which converts the rotation of the output shaft of the motor into displacement of the desired portions of the bed.
Experience with the adjustable beds of the conventional constructions has shown that, as advantageous as they may be in various respects, they all suffer from a serious drawback which resides in the fact that, when an external obstruction hampers the displacement of the mattress and/or its movable support structure at any region thereof, the remainder of the mattress and its support structure continues its movement unimpeded, so that the mattress begins to tilt, typically toward one of the sides of the bed, and continues tilting unless the operation of the motor is discontinued by the patient or an attendant or nurse, until the degree of the lateral tilt is such that the patient may be thrown against a raised side guard rail of the bed, or if the guard rail is lowered, the patient may be caused to fall off the bed. This, of course, is highly undesirable, since it can result in injury to the patient, aggravation of an already existing condition, or disconnection of various life-support apparatus with attendant grave consequences. Of course, this possibility could be avoided if the attendants or nurses were paying attention not only to the operation of the bed, but also to the presence of possible obstructions in the path of movement of the adjustable part of the hospital bed. Unfortunately, this cannot always be assured, so that it occasionally happens that the mattress of an adjustable bed moves into its undesirable tilted position, and the patient is at least inconvenienced, if not injured.